In an excerpt from the book, Tannen writes about discussing sisterhood with a group of women at a party, including one named Laxmi who said, "When we meet we can't get enough of each other. When we ride in a car together, my husband threatens, 'I'm taking another car! You two never stop talking and laughing!' She's my lifeline. I'm her lifeline. If I say one word, she knows what I'm going to say. We've made a pact that we'll take a vacation together at least once a year." This sweet depiction of the sisterly bond prompts another woman to remark, "That's why I always wished I had a sister."

Frankly, the same thought crossed my mind, and I have two sisters. I love them dearly, but for every time one of them has finished my sentence or laughed at an inside joke based on a single word or gesture, I can think of another time when one of them has told me I'm ugly, gotten me in a headlock, made fun of my goals, made me sick with worry, kicked me in the shins, gotten me in trouble for something she did, reminded me how very much I suck, stolen my shit, or spent an entire vacation whining about everything I wanted to do. And that's the stuff that didn't require therapy. So I was perversely gratified to read the rest of Tannen's story, in which Laxmi admits to the author privately that she and her sister hadn't spoken to each other for a year, following an enormous falling out over money. Ah, that sounds more familiar!

Writes Tannen, "The word 'sister' evokes an ideal of connection and support, like the friendships that made Rebecca Wells's Divine Secrets of the Ya-Ya Sisterhood and Ann Brashares's The Sisterhood of the Traveling Pants into bestselling novels and successful films" — i.e., stories that weren't about actual sisters. (Some books-to-films that were: Whatever Happened to Baby Jane?, Atonement, My Sister's Keeper. Just saying.) And that's one of my biggest beefs with the pervasive idea that sisterhood is necessarily some magical bond, infinitely deeper than mere friendship: When it works, it's the friendship that makes it look so great. I do know lots of women who consider their sisters their BFFs, and they're lucky — but are they any luckier than I am, with two sisters I both like and love but don't categorize as besties, plus a great, non-related BFF? Or the BFF herself, who's an only child? I have no way of knowing — and neither does anyone else — but I can tell you I'm pretty damned lucky.

I can also tell you that the "sisterhood is better than any friendship" concept makes a whole lot of women feel inadequate and left out — notably women without sisters, but also sisters of women who are an exhausting load of work to love and support for any number of reasons, women who have zero in common with their sisters, and mothers of only children, who are constantly scolded for denying their kids that magical bond. It strikes me as part and parcel of our culture's fetishization of the traditional family — two married, healthy, heterosexual parents, and at least two healthy, attractive and charming children — which undermines the value of primary loving relationships that fall outside that description. Whether you're queer, living in sin, a single parent or someone raised by one, an orphan, a foster parent, the caretaker for a sibling with a severe illness, or an only child, you don't fit the mold. And you're told repeatedly that you can never be as happy and fulfilled as people who do.

Bullshit. Deep, enduring love comes from many sources other than blood ties, and often enough, the love that does come from those ties can be destructive. I was so happy to see that Tannen gets right to acknowledging the more difficult aspects of sisterhood, because it's so often painted as nothing more than "an ideal of connection and support" that resonates with many women about as much as your average Hallmark card — yet can still make us wonder what we're missing. The ideal of a "best friend who can never leave you" sounds nice on the surface, but what if she feels more like an albatross who can never leave you? And what of the best friends who can leave you but choose to stay year in, year out? Are they less important because they don't have any embarrassing stories about your toddlerhood? Or any less "sisterly," for that matter?

Of her sister, one woman told Tanner, "I love her to death. I can't imagine life without her." Another said, "I don't want anyone to kill my sister because I want to have the privilege of doing that myself." As someone with sisters, I can relate to both comments. A lot. But so can people without sisters, because those mixed feelings can be part of any emotionally intense, long-term relationship, including many that don't get their own section in the card aisle.